True about active transport of the drug across a membrane except

• A. I, III, IV
• B. II only
• C. I, II, III, IV
• D. II, IV

Answer: (B)

Active transport moves a drug across a membrane against its concentration or electrochemical gradient and requires energy, typically via a carrier protein. Because it works against the gradient, it is energy-dependent, saturable (finite carriers), and usually specific for the drug. It can involve direct ATP use (primary active transport) or rely on an ion gradient (secondary active transport). Any statement that says no energy is required, that movement occurs with the gradient, or that a carrier isn’t involved does not describe active transport. The correct choice points out only the statement that aligns with the energy-dependent, carrier-mediated, gradient-against nature of active transport, while the others describe properties of passive diffusion or carrier-independent processes.